Is it possible to “baste” hard rubber dog toys to make them more appealing?
As far as I know, “basting” won’t make any difference with rubber toys. I do know that some rubber toys come with an unappealing smell and/or taste (according to dogs anyway). Try buying a new brand that smells differently; my dogs have been very picky about certain brands in the past. A good rule of thumb for me so far has been that if it smells nice to me (e.g. vanilla or whatever), chances are that it won’t smell appealing to the dogs. Otherwise, you might try to bury the toy in the ground for a while or give them old shoes that you don’t wear anymore (always a winner). Good luck!